Audio jacks are used to interconnect various pieces of audio equipment. One such audio jack has first and second jack ports on the front of a jack housing, at least a first contact associated with the first jack port at the rear of the jack housing, and at least a second contact associated with the second jack port at the rear of the jack housing. The first contact can be referred to alternatively as the bottom contact, the second contact can be referred to alternatively as the top contact, the first jack port can be referred to alternatively as the bottom jack port, and the second jack port can be referred to alternatively as the top jack port.
Let it be assumed that the operation of this jack as described below in this paragraph is the normal operation of the jack. When no plug is inserted into either jack port, the first and second contacts are coupled together. However, when a plug is inserted into the first jack port, there is no coupling between the first and second contacts, and the first contact is instead coupled to the plug in the first jack port. Similarly, when a plug is inserted into the second jack port, there is no coupling between the first and second contacts, and the second contact is instead coupled to the plug in the second jack port.
Normalling of the jack refers to changing the operation of the jack. It is desirable for a jack to have full normal operation, half normal operation, and no normal operation. Full normal operation of the jack is described in the preceding paragraph.
During half normal operation of the jack, the first and second contacts are coupled together when no plug is inserted into either jack port. When a plug is inserted into the first jack port, the jack operates according to its full normal operation. That is, when a plug is inserted into the first jack port, there is no coupling between the first and second contacts, and the first contact is coupled to the plug in the first jack port. However, when a plug is inserted into the second jack port, the first and second contacts remain coupled together and the second contact is coupled to the plug in the second jack port. When plugs are inserted into both the first and second jack ports, the first contact and the first jack port are not coupled to the second contact and the second jack port so that there is no cross coupling. Accordingly, the first contact is coupled to the first jack port, and the second contact is coupled to the second jack port.
During no normal operation, no signals are routed between the first and second jack ports. Each jack port is isolated from the other. Signals may flow between the first contact and the plug in the first jack port and between the second contact and the plug in the second jack port. Signals may not flow between the first contact and the plug in the second jack port, between the second contact and the plug in the first jack port, between the first and second contacts, or between the first and second jack ports.
Various designs have allowed a jack to be normalled. For example, wiring between jack ports and external jumper pins have permitted removable jumpers to be used to change the normalling of jacks. Such wiring and jumpers have been used either behind the jacks on a patchbay panel, or in front of the jacks with some sort of covering. Removable jacks have also been used so that jumper wires or clips could be removed or repositioned to affect the normalling of the jack.
The present invention is directed to a jack that allows for the changing of its normalling without removing the jack from the panel, and without the use of external parts such as jumper wires or clips that can be lost or applied incorrectly. Instead, switching is provided to control normalling of a jack according to the present invention. The switching is internal to the jack.